Bheostat



3 Sheetsg-Sheet 1. J. C. FYFE. RHBOSTAT.

(No Model.)

Patented Apr. 9, 1895.

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JOHN C. FYFE, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALE TO JAMES HAYES, OF SAME PLACE.

RH EO STAT.

SPECIFICATION forming part of Letters Patent No. 537,412, dated April 9, 1895.

Application filed January 24, 1895. Serial No. 536,080. (No model.)

T 1f/ZZ 10700771/ it may @0N/067%: electro-magnet through which the current Be it known that I, JOHN C. EYFE,a citizen may pass; to provide a more perfect contact, of the United States, residing at Chicago, in and at the same time less friction and wearthe county of Cook and State of Illinois, have ing of the contacts; to provide a direct maginvented certain new and useful Improvenetic contact permitting the use of iron con- 55 ments in Rheostats; and I do hereby declare tacts which are preferably in the form of the following to be a full, clear, and exact derollers, thereby allowing free action of the scription of the invention, such as will enable contact arm which may, if in the proper poothers skilled in the art to which it appersition, fall of its own weight when released 1o tains to make and use the same. by the current falling below the required 6o This invention relates to rheostats, but strength; to utilize the bare magnet core or more particularly to those known as startingcontact plate as a terminal to the sections of boxes for electric motors. the resistance; to aid, by magnetic adhesion For some time the tire inspectors have, in or attraction, the usual spring-actuated conmany places, required that the starting-boxes tacts, thereby reducing the spring tension on 65 for electric motors shall be made to open the the contact arm to a minimum; to provide motor circuits automatically; that a double electro-magnetic contacts, the windings of pole switch shall be placed between and in which form sections of the resistance; and to circuit with the starting-box and the main or provide conductors for the current which zo leading, in wires; and that this switch must may be utilized for many other purposes than 7o always be opened after the motor is stopped for a rheostat or starting-box, by applying to avoid the danger of res from grounds, its heretofore wasted energy to assist in inlightning and the like. This later requiresuring its own circuit completeness at the ment has resulted in more or less disaster contacts.

and annoyance at the electric power stations, Further objects of the invention are to 75 as the error frequently occurs of irst throwprovide a magnectic arc-rupturing factor; to ing the starting-box into circuit, thereby closprovide ample ventilation, a fire-proof suping the armature circuit of the motor, and afport to each coil of resistance, and an autoterward closing the switch by which the full matically operated switch; to provide a maxi- 3o force of the current is suddenly thrown on the mum and a minimum release for the contact 8o motor, without having first had the benefit of arm; and to provide means to insure safety the cushion of the resistance in the startingin case of overloading of the contact. boX and allowing the armature to get into mo- Vith these and other objects in view, the tion. Such mistake results in the instantainvention consists in the means substantially ncous short circuiting of the system and often as hereinafter described and more particu- 85 blowing the fuses at the power station, as larly pointed outin the claims at the end of they may be already loaded nearly to their the description. full capacity, thereby temporarily disabling Referring to the accompanying drawings, the entire system. forming a part of this specification, Figure l 4o The primary object of my invention is to is a side elevation of a starting-box with the 9o overcome this objectionable feature by profront plate partly broken away to enable the viding means whereby the making of the underlying parts to be seen, the resistance armature circuit is prevented untilthe switch being shown diagrammatically. Fig. 2 is an is closed; to provide means for simultaneend elevation with the contact lever partly ously closing the switchl and the motor armabroken away to show the initial contact plate. 95 ture circuit; and to provide a switch through Fig. 3 is a sectional view on the line III-III which the negative and positive feedwire of Fig. 5, illustrating the spring contacts of circuits must be closed before the resistance the switch and the manner of insulating said and motor armature circuit can be closed. contacts from the supporting bracket or arm.

5o Other important objects are to provide an Fig. 4 is a section through the contact roller, Ico

taken on the line lV-IV of Fig. Fig. 5 is a fragmentary View looking from the side of the starting-box opposite that of Fig. l,illus trating the circuits open,and how the end of the switch-supporting arm interlocks with that of the contact arm. Fig. 6 is a detail sectional View through one of the resistance coils showing the contact plate in elevation. Fig. 7 is an end elevation of a contact plate the resistance being in section. Fig. 8 is a fragmentary view partly in section, illustrating the minimum and maximum release for the contact. Fig. 9 isa sectional view, partly broken away, taken on the line lX-IX of Fig. S. Fig. lO is a diagrammatic View, illustrating the application of my invention for controlling an electric motor; and Fig. ll is a diagrammatic View of a modified form of my invention.

ln the drawings, A may designate a frame of any preferred form or construction, but preferably composed of two plates of slate or other suitable material d and a', which are held apart by the sleeves a2 through which are passed the binding bolts a3. These bolts may be separated from the sleeves by a lining of asbestos or other insulation a4 as an extra precaution against grounds and the like, and pass through the plates and the supporting feet d5 at proper points to properly bind the Whole together, the said supporting feet being adapted to be secured to an insulated switch beard, or its equivalent, by the screws d6.

Secured to the inner sides of the plates d and d are the positive switch contacts l), ZJ', and the negative switch contacts b2, b3, arranged above said positive contacts, each contact being connected with its respective binding post secured to the outer surface of the frame plates. Arranged to engage these contacts is a double pole switch C having asupporting arm c secured to a bracket c which is pivoted at c2 to standards c3 extending out- Wardly from the plates d and ct. This switch preferably comprises a pair of U-shaped spring contacts c4, c5, insulated from each other and from the supporting arm c by a block of insulation c, preferably of' slate, to which the spring contacts and the supporting arm are secured by screws or otherwise, the said screws or fastening devices being properly insulated to prevent leakage between adjacent parts. lhe spring contacts of the switch are adapted to span the positive and negative contacts and are normally pressed out of engagement therewith by a spring c7 one end ot' which bears against the under surface ofthe supporting arm, while the opposite ends are secured to the standards c3. The supporting arm c has its inner end cs, curved and extending into the frame between the plates cty and d adapted to bear on the calnshaped end d of a contact arm D.

The contact arm D is rotatably supported on a pin or shaft d', which has its ends pref erably screw-threaded and passed through the plates to which itis secured by the nuts d2; the said arm being separated from the plates a and a. by metallic washers d3. This arm is provided with a suitable projection dl adjacent to its cam-shaped end d which serves to form an abrupt recess d5 in which the curved end c8 of the supporting arm is adapted to fit when the switch is open to limit the outward movement of said switch and the downward movement of said contact arm, thereby forming an interlocking connection between the two, as shown in Fig. 5. The outer end of the contact arm may be provided with a handle d, of any preferred form, and has extending therefrom a bow-spring dT, on the end of which is arranged the contact rollers e. This contact e is preferably composed of a series of disks of magnetizable metal= preferably iron, separated from each other by close fitting washers to insure contact with their support and prevent possible fusion between any pairs, and are loosely mounted to rotate on a stud or pin c' carried by a bracket e2 which is secured to or formed integrally with the bow-spring d?, as best shown in Fig. l. These disks are loosely fitted to the pin e to permit a multiplicity of contacts at each of the attracting contact-plates or cores F.

The contact plates or cores F may be of any desired width, length or thickness according to the resistance f wound upon them, which is determined by the voltage and the required capacity. These contact plates are preferably punched or otherwise formed from soft strap iron and are arranged so that each core or plate forms a radius with the pin tl as the center; the said plates or cores being bent downward at their outer ends to form a better contact surface for the rollers e, and having projecting lugs f on opposite sides there- 0f, which are inserted into corresponding apertures f2 in the inner sides of the plates d and a of the frame, by which they are rigidly held from displacement.

The resistancef is preferably prepared in accordance with the process disclosed in the patent granted to myself, No. 528,539, of November 6, 1894. In the present case l may use a piece of insulation f3, preferably asbestos, saturated with silicate of soda and pasted over each edge of the contact plate where the resistance is to be wound, and of sufficient thickness to suspend the resistance across the sides of the cores F, thus permitting ventilation, as best shown in Fig. 2. The cotton covered resistance or coil is now wound on each insulated contact plate or core, after first being saturated with the silicate, the ends of each coil being cleansed and having one of its ends forced into a slit f4 (Fig. (i) enough, however, of the end remaining to make connection with the adjacent coil. These are now subjected to sufficient heat to burn the cotton covering and crystallize the silicate, when they are ready to be assembled as heretofore explained. The coils or resistancesf preferably comprise one layer of wire,

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and alternate both as to their connection with the adjacent coil and as to their connection with the slits in the plates or cores. If these plates were not connected with their respective resistance coils, the plates would become simple magnets when the current passed through the coils, but as they are connected to one end of their respective coils, they become contact magnets, or magnetic contacts. The contact rollers cserve to bridge two adjacent plates, thus short circuiting the otherwise open magnetic circuit, creating thereby a magnetic circuit through said plates and rollers, which Varies in intensity according to the position of said rollers and the amountof resistance in circuit.

The upper contact plate F needs no connection with its respective coil as its inner end is bent downward at f5 and bya screw]6 is attached to the adjacent plate Fthus getting its connection through said latter plate. The binding together of the lower ends of these plates not only constitutes an electric connection, but also completes one-half ofthe magnetic circuit, the latter creating thereby a material increase in magnetic power. The object then of the position given to the other contact magnets is obvious, as it will be seen that to allow them all to touch at their lower ends would shortcircuit the resistance, but as they are placed as close as practicable yet at a safe distance apart, they derive, (by exposing to each other as much of the sides of their inner ends as possible) a material increase in their magnetic value, over what it would be were they placed parallel. The plates F and F2 need not be wound with iron wire, as preferably used on the others, but with copper wire of sufficient capacity to constantly carry the maximum load in ampres required, the end of the coilof the plate or core F being connected to the binding post g.

For releasing the contact rollers e when the current is reduced in strength I preferably provide a spring contact g secured to and eX- tending outwardly from the contact plate F' which is adapted to abut against a curved contact spring g2, carried by the bow-spring d7 of the contact arm when the full force of the current is utilized. These contact springs oppose the attraction of the magnets formed by the plates F and F2 so that when the current is reduced from any cause sufliciently to allow the springs to overcome the attraction of the magnet the contact arm will fall of its own weight. These contact springs form a minimum release, and serve to insure a passage for the current under a heavy load.

To prevent injury from an overload or undue ampere strain being thrown into the current either by overloading the motor, by lightning, grounds or short circuits either in the generator or across the negative and positive wires or connections, I provide a maximum release comprising an armature 71. adapted to shunt the magnetic field formed by the magnetzed plates F and F2, as best shown in Figs.

Sand 9. This armature or magnetic shunt 7L is preferably made of iron, and has two projecting ends h', h', which are bent upward and pass through countersunk apertures in the upper portion of the plate F2; the countersinking giving free movement to the magnetic shunt, while the bent ends of said magnet shunt serve to hold and limit the movement of the same. The outer end of the magnetic shunt is adapted to contact with the plate F and is attached to the end of abent spring h2 which p'asses through one of the plates and is secured to the outer surface of said plate, the bent portion of the spring having an adjusting screw h3 for varying the resistance of said spring. The magnetic shunt has a greater surface exposed to the magnet than the contact, which is,in this case, round. By placing the magnetic shunt with one end in contact with one of the poles and having a superior contact surface'at the other end within reach and in influence ofthe surplus n1agnetism,will, upon gaining sufficient power to overcome the adjusted tension spring, attract the shunt magnet h and instantly divert sufficient of the magnetic current to cause the contact to roll away or fall of its own weight. This places the resistance in circuit, thus reducing the heavy current ampres which caused the release of the contact rollers.

The operation of the device will be readily understood from the foregoing description and the accompanying drawings. It will be seen should the parts be in the position shown in Fig. 5 and the positive and negative con'- tacts connected with the positive and negative wires of the line, that by moving the contact lever D, the end of the supporting arm c of the switch will be released and the camshaped end dof said lever caused to force the switch against the teution of the spring c7 to close the circuit through the positiveand negative contacts before the contact roller e has reached the initial contact plate F3. As will be seen, by tracing the circuit in Fig. lO, for a shunt wound motor, the field circuit through the motor has been closed with the main or line wires, by the spring contact c4 of the switch, wires m, field of the motor M, wire m to the negative switch contact b2, spring contact c5, contact b3, to the line, thus energizing the field for the armature when the circuit is closed, which occurs with all the resistancein series by continuing the movement of thc lever D till the contact rollers c engage the initial contact plate or core is. In forcing the rollers thus, the spring bow dl causes the rollers e to bear on the magnet contacts, according to the inward tension of said spring and the added adhesion of the now magnetized contacts. The circuits being established,

through the resistance, the current passes from the positive switch contact l) or its binding post, wire m2 leading therefrom to the washers d3 which bear against the contact arm through the contact arm D, rollers e,

contact plate or core, its resistance f, the

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remaining coils, to the binding post g, wire 'm3, through armature to wire m and to the negative contact b3, spring contact c5, contact b2, then to the line. As has been described one end of each resistance coil connects with its respective Contact plate orcore; and as the contact rollers e pass upward over them, the said contact plates are one at a time cut out of the armature circuit, thus reducing the resistance and increasing the power of the motor. When the rollers c have reached the position, shown in Fig. I, the rheostat resistance is now out of circuit and the motor is at its full capacity, and the current is passing not only through the contact plates F, F2, but through the spring contacts g2 and g to said plates. Should the current be now reduced or increased in strength, from any cause, sufticient to allow the contact arm to fall and open the circuit as heretofore explained, the switch spring c7 bearing against the supportingr arm c will cause'the curved end of said arm to slide over the cam-faced end d of the contact arm D, without, however, moving the switch contacts until the abrupt recess d5 is reached, when the end cS of the supporting arm slides into said recess, allowing the switch spring to throw the switch open suddenly. The constant upward pressure of the switch spring has no eii'ect on the switch or contact arm D until the abrupt recess is reached, which occurs, as seen in Fig. 5, when the line between the centers of the pins c2 and d has been crossed, or not in direct line with the pressure of said sprinr. At the point of crossing,the contact rollers e have not reached the initial contact. rlhus the switch does not open or begin to open until the resistance is nearly all again in the circuit. Before the switch contacts have reached the breaking point, the contact rollers e leave the initial contact plate, and any excessive spark or arc, if any at all, occurs at this contact point, which is magnetized by its resistance winding, the combined magnetic arc-rupturing effect of which, together with the resistance which reduces the amperes, renders the spark harmless, thus making` a magnetic arc-rupturer at this point.

.It is obvious that I may use many of the parts for other purposes than for a startingboX or rheostat, nor do I confine myself to the numberof poles the switch may have, for when the system demands it, a single,double, triple, or other suitable switch may be employed if desired.

In some cases the switch maybe dispensed with entirely, as illustrated in Fig. Il. I'lere the device is shown as simply controlling the armature circuit of an electro-motor, while the field may be excited directly from the mains or in any other proper manner. The supporting arm c is somewhat shorter than when the switch is employed but is otherwise similar to that of the preferred form. The frame plates are shown square which is the form preferably employed in large starting-boxes and rheostats, where greater length of contact plates is desired. Instead of allowing the contact arm to fall by gravity, a spring may be supplied to return the same to open position, or different contacts may be supplied if desired.

I may dispense with some of the parts, or substituteother constructions for those shown, and I therefore do not wish to confine myself to the exact construction shown, as this may be changed in some instances, without departing from the spirit of my invention.

I have described the rolling contact as comprising a series of rollers e, but it is obvious that I may employ a single roller if so desired.

IIaving thus fully described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is

l. In a device of the character described, the combination with suitable resistance, of a switch adapted to be thrown into and complete the circuit with the mains before the resistance can be placed in circuit, and means for preventing the opening of the switch before the resistance circuit is open, substantially as described.

2. In a rheostat or starting-box for electric motors, the combination with a suitable resistance, of a switch controlling the mains or leading in and leading out wires, said switch being adapted to be thrown into circuit with said mains before the resistance can be placed in circuit, means for simultaneously operating the switch and placing the resistance in circuit after the switch has been closed, and means for automatically opening the switch after the resistance is open, substantially as described.

3. In a rheostat or starting-box for electric motors, the combination with an electric motor and a suitable resistance included in the armature circuit of said motor, of a switch controlling the mains or leading in wires, Said switch being adapted to be thrown into and complete the circuit with said mains and the field circuit of the motor, means for simultaneously operating the switch and placing the resistance in circuit after the switch has been closed, and means for automatically opening the switch after the resistance is open, substantially as described.

4. In a rheostat, the combination with a suitable resistance, 0f a switch controlling the mains orleadingin and leading out wires, said switch being adapted to be thrown into circuit with said mains before the resistance can be placed in circuit, an arm adapted to close or open the resistance circuit and for simultaneously closing the switch before the resistance is placed in circuit, together with a spring for automatically opening the switch after the resistance is open, substantially as described.

5. In a rheostat, the combination with suitable resistance, of a contact arm adapted to close or open the resistance circuit, a switch operated by said arm for throwing said switch IOO IIO

into circuit with the mains, together with an interlocking connection between said arm and the switch for limiting the outward movement of the same, substantially as described.

6. The combination with suitable resistance, of a contact arm adapted to close or open the resistance circuit, and a second arm for simultaneously operating the rst-mentioned arm and having an interlocking con- Io nection with said contact arm for limiting its outward movement, substantially as described.

7. In a rheostat, the combination with suitable resistance, of adouble pole switch adapted to be thrown into and complete the circuit with the mains before the resistance can be placed in circuit, a contact arm for operating said switch and for closing or opening the resistance circuit, together with means for preventing the opening of said switch before the resistance circuit can be opened, substantially as described.

8. The combination, with a pivoted arm having a cam-shaped end and an abrupt recess in said end, of a second arm having one of its ends curved and adapted to bear upon and be operated by the cam-shaped end of the first mentioned arm and to enter the recess in said end to form an interlocking connection therewith, together with a spring for opening said second arm, substantially as described.

9. In a rheostat, the combination with a suitable support, of a switch comprising a pairot U -shaped spring contacts insulated from each other and adapted to be thrown into circuit with the mains, an arm pivoted to the support and insulated from said spring contacts, a spring arranged to automatically open said switch at a predetermined point together with a second arm for placing the switch in circuit with the mains and for controlling the movement of said spring, substantiallyas described.

l0. In a rheostat, a magnetic contact comprising a core, an insulating medium partly surrounding said core forming an open space thereby, and a resistance coil passing around the insulation and suspended over the open space to permit ventilation, substantially as described.

5o 1l. In a rheostat, a contact comprising a core of soft iron, and a section of the resistance surrounding said core and insulated therefrom, the said core forming one terminal for said resistance, whereby the said core may serve as a magnet and convey the current,

substantially as described.4

12. In a rheostat, the combination with a series of magnetic contacts, of a magnetizable contact adapted to engage said magnetic contacts, substantially as described.

13. In a rheostat, the combination with a series of magnetic contacts forming terminals for sections ofthe resistance circuit and to convey the current to said resistance sections, of a series of rolling magnetizable contacts adapted to close or open said resistance circuit, substantially as described.

14. In a rheostat, the combination with a series of magnetic contacts forming terminals for the resistance circuit, of a magnetizable 7o contact adapted to close or open said resistance circuit, together with a minimum release for forcing said contact away from its magnetic contact when the circuit is sufliciently reduced in strength7 substantially as de- 75 scribed.

l5. In a rheostat, the combination with a series of magnetic contacts forming terminals for the resistance circuit, ot' a magnetizable contact adapted to close or open said resistance circuit, together with a maximum release for allowing said contact to recede from its magnetic contact when thecircuitis increased beyond a predetermined point, substantially as described.

16. In a rheostat, a magnetic contact forming a terminal for a section of the resistance, and to convey the current to said section of resistance substantially as described.

17. In a rheostat, the combination With a series of magnetic contacts forming terminals for the resistance circuit, of a magnetizable contact adapted to close or open said resistance circuit, together with a minimum release comprisingaspring secured to one oi' the mag- 95 netic contacts and adapted to abut against a second spring carried by the contact, substantially as described.

I8. The combination with a magnetic contact, of a contact adapted to engage said mag- 10o netic contact and be held thereby, together with a magnet shunt for short circuiting the magnetic iield of said magnetic contact for releasing said contact, substantially as described.

19. The combination, with a magnetic contact having a north and a south pole adjacent to each other,ot` a contact adapted to engage said magnetic contact and be held thereby, together with a spring-retained magnet shunt 11o engaging one pole and adapted to be placed in contact with the other pole to short circuit the magnetic field to release said contact when the magnetic attraction is sufticient to overcome the tension of the spring, substantially as described.

20. In a rheostat the combination with a magnetic contact formed by the resistance passing around the same and having a north and a south pole adjacent to each other, of a 12o rolling contact adapted to engage said magnetic contact and be held thereby, a magnet shunt engaging one pole and adapted to be placed in contact with the other pole, and a spring for normally holding the magnet shunt 1 25 open, whereby the magnetic contact may be short circuited to release the rolling contact, substantially as described.

21. In a rheostat, the combination with a series of magnetic contacts forming terminals 13o IOS for the resistance circuit, of an arm carrying a magnetizable contact adapted to open and close the resistance circuit, together with means for permitting the arm to open the resistance circuit, substantially as described.

22. In a rheostat, tbe combination with a series of magnetic contacts radially arranged and having their inner ends exposed to each other and forming` terminals for the resistance circuit, together with a inagnetizable contact for opening and closing the resistance circuit, substantially as described.

23. In a rheostat, the combination Wit-l1 a suitable resistance, of an arm,and a series of contact disks adjacent to each other and loosely mounted upon a single stud androtatably held on said arm adapted to open or close the resistance circuit, substantially as described.

24. In a rheostat, the combination with a series ot' magnetic contacts forming terminals for the resistance circuit, of a rolling magnetizable contact adapted to close or open said resistance circuit, substantially as described.

In testimony whereof I affix my signature in presence of two Witnesses.

JOIlN C. FYFE.

Witnesses:

W. E. MCHENRY, JAMES HAYES. 

